Apparatus for producing biscuits



March 1939- w. P, MORTON APPARATUS FOR PRODUCING BISCUITS OriginalFiledMay 26, 1936 mm m 3 w w WWW mw La Z? Z Z L im a m i INVENTORWILLIAM PRESLEY M0 0N v ATTORNEY Patented Mar. 7, 1939 Aren't FAPPARATUS FOR PRODUCING mscm'rs William Presley Morton, Indianapolis,Ind.

Application May 26, 1936, Serial No. 81,836 Renewed September 27, 1938.6 Claims.

vention is applicable with especial value in the baking ofdough whichrequires a quick initial spring, i. e. a sudden expansion of leaveninggases and vaporization of moisture at the outset of the baking, as inthose sponge doughs for soda crackers and the like.

Among other objects, the invention. is intended to provide means for thesuperior application of heat to the dough, to suit varying kinds andconditions, and particularly to insure the quick initial spring indoughs-that need it; and also to provide for thedisposal of moisture atdesired stages and in proper'degrees in the baking process.

An illustrative form of apparatus is shown in the accompanying drawing,in which Fig. 1 is a diagrammatic side elevation of the major featuresof the apparatus Fig. 2 is a vertical section on of Fig. 1;

Fig. 3 is a detached vertical section on the line 3--3 of Fig. 1;

Fig. 4 is a plan view of afragment of an illustrative form of perforateconveyor belt usthe line 2-2 able in the apparatus and method indicatedin Fig. 1. I

The drawing shows an illustrative oven structure through which passesan. endless conveyor 5 of special construction presently described. Theconveyor is mounted upon a driven drum 6 and a second drum '7 at theopposite extremity of the oven. The drum 6 has fixed thereon a gear 8 towhich is applied the drive, from any suitable source ef power, forcausing the conveyor to travel in the direction indicated by the arrows.The drum 6 and its gear 8 rotate upon a hollow shaft 9, through whichheat is communicated to the interior'of the drum 6 to maintain it atdesired temperature, andthereby to aid in keeping. the conveyor at thetemperatures desired, as presently explained. For example, the hollowshaft 9 may be connected with a source of fuel which may pass throughthe jets Ill, and may be ignited through the aperture 'II in one end ofthe drum. A regulating cock (not shown) will be provided in the fuelconduit so that the heat in the interior of the drum 6 may be gov ernedto maintain proper temperature and to vary it to suit differentrequirements.

The conveyor 5 is of distinctive character, formed of metal, or acomposite of metal pieces, preferably combining two importantcharacteristics, namely: that it shall constitute a relatively heavyheat-retaining body of metal, and that it shall be equipped with amultitude of air passages extending through it. One desirable form ofthe conveyor 5 is composed of metal, steel for example, of suchstructure and dimensions that a section of the conveyor having an areaof 1 sq. ft. weighs approximately 5 to 8 lbs., or even more. Anappropriate type of conveyor is indicated by the fragmentary plan viewin Fig. 4, in which are shown the transverse bars i3 which extend vacross the width of the conveyor, interconnected by coiled bars l4resembling somewhat, in mechanical principle, the sort of conveyor beltshown in Fig. 1 of the patent to Edgar Pattee No. 1,204,816 datedNovember 14, 1916. The edge of the conveyor may be formed byspot-welding together the extremities of the coiled bars it and thetransverse bars I3 as indicated at it, and the alternating bars l3 maybe headed as indicated at l6. The cross sections of the bars 53 and M,the dimensions and pitches of the coils, and the coordination of thetransverse and coiled bars, are such that, as already said, the con-.veyor having a receiving area a foot square weighs approximately 5 to 8lbs. or more. At the same time, the interstices between the bars supplya multitude of air passages through the conveyor.

vFor reasons later explained, in some aspects of the invention it ispreferred that the biscuit or the like deposited upon the conveyor be inseparate pieces, for the respective biscuit, with "edges spaced apartsufliciently to permit free circulation of heat uniformly around theperiphery of each biscuit and between contiguous biscuits. In Fig. 4the'dot and dash circles, respectively, indicate individual biscuit asthey may be deposited on the conveyor, spaced apart so that currents ofhot air passing through the interstices of theconveyor may completelyencircle each biscuit with substantial uniformity.

' The bars It may be of any desired cross section,

and the convolutions of their coils may have more or less -'urvaturewith the result that the supporting surface of the conveyor is composedof numerous small separated surfaces against which the biscuit havecontact along rather narrow lines or at individual points. The specificbars I4 of Fig. 4 are circular in cross section, which is one desirableform. When the biscuit are thus supported upon the irregular surface ofthe conveyor, each b scuit being positioned over and substantiallyencircled by interstices in the conveyor, there is opportunity for thedirect apmore or less horizontal wall 22 formed of slabs of firebrick orthe like. In the lower part of the chamber are the burners 25, 25 whichillustrate any practicable source of heat for creating and maintainingdesired temperatures in the chamber. For example, the burners 25 may besupplied with fiuid fuel through the pipe 26. Additional burners 28 maybe located between the conveyor 5 and the ceiling 22. In some instancesit is preferable to supply these burners 28 in the vicinity of thedischarge end of the oven so that the heat from them may contribute tothe later stages of the baking of the biscuit.

In baking some kinds of biscuit, considerable moisture is driven ofifrom the dough in the form of steam. The steam'emerges from both the topand under surfaces of the dough. When the dough rests upon animperforate hot plate or conveyor, the steam at the under surface of thedough is likely to be trapped between it and the plate and to formconcavities in the dough,

largely because there is no adequate opportunity for the steam toescape. The result is that the under face of the baked dough is pittedby irregular pockets, frequently of considerable size, and the dough isunevenly baked and browned on its lower surface partly because thetrapped moisture somewhat insulates the dough from the heat of theplate. These defects in method and product are avoided or minimized inpracticing the present invention because the steam can readily escapefrom beneath the dough through the passages formed by the irregularsurface of the conveyor, and also because the perforations orinterstices in the conveyor serve as miniature chimneys for currents ofhot air or gases which may impinge against the under surface of thedough, flow through the described passages and carry away the steam,instead of leaving it trapped beneath the dough. The substantialheat-retaining capacity of the relatively heavy metal in the conveyorenhances these beneficial effects by maintaining a substantial heatsupply adjacent the dough to aid in maintaining the currents to carryaway steam.

It has been a familiar practice in the prior art.

sulting defects in the baking and the product. 4 -When docker holes areemployed in the use of this invention, there is a direct cooperationbetween the docker holes and the perforations or interstices in theconveyor, such that the former function as continuations of theminiature chimneys through the conveyor facilitating the flow of thedescribed currents of hot air or gases and the carrying away of thesteam.

When an imperforate oven plate or band is employed, the air and moistureabove it has a tendency to be more or less inert and to becomestratified in layers of different respective temperatures, with theresult that excess moisture or steam may be present at the upper surfaceof the dough and may cause an objectionable glaze or crust on the topsurface which interferes with proper drying and baking. But in the useof a heavy heat-retaining conveyor having of the chamber, and also withnumerous vents 3|, 3| toward the discharge end of the chamber. Thesevents lead through the ceiling 22 into one or more auxiliary chambers 33connected with an exhaust pump 38. through a pipe coupling 35. Theeffect of the exhaust pump is to draw air and moisture out of theauxiliary chamber 33, and through the vents 30, and 3|, 3| from the mainoven chamber. For regulating the vents 3G, to close them entirely or toopen them to the maximum or to vary their eiiective cross sections, avalve plate 31, having apertures corresponding to the vents 3B, 30, ismounted upon the top surface of the ceiling 22 and is arranged to slide(right and left in Fig. I) to close, open orregulate the vents 38, 30.As shown inFig. 2, the valve plate 3! slides beneath keepers 38 mountedon the ceiling structure, and is equipped with ears 39 for theattachment of the lower end of an adjusting handle 40 pivoted at 4|.above the top wall of the ceiling structure. The passage through thattop wall for the depending stem of the adjusting handle 49. supplieslimiting stops for the extremities'of adjustment of the valve plate 31.For regulating the second series of vents 3|, 3|, a separate valve platemay be provided, to be adjusted by a handle 66. With this arrangement,suction vents at different locations in the oven may be separatelyregulated to suit different conditions. For illustration, in someinstances it may be desirable to have the vents toward the entrance endof the oven widely or largely opened, while those toward the dischargeend of the oven are restricted or entirely closed. Or the reverse may becalled for under some circumstances. Or it may be desirable to have allthe vents, in the plurality of groups thereof, similarly opened orentirely closed. Besides performing the functions just described, thearrangement of the ceiling vents under the influence of the suction pump3d may be utilized to cause a flow of hot air, or air and moisture, inone direction or another relative to the movement of the conveyor 5. Forexample, if the vents 30 be wide open and the vents 8| becompletelyclosed, the operationof the suction pump 36 may be regulated so as tocreate a considerable flow of heated air upwardly, through the vents 30,and while this would draw air and moisture from the vicinity of theentrance end of the oven, it would also create a current through thechamber in a direction generallyopposite to that in which the upper runof the conveyor is traveling. A similar efieot, but creating a currentin the same direction as that of the travel of the conveyor, could beproduced by closing the vents 38 and opening the vents 3|.

A material part of the baking function is performed by heat reflected orradiated from the amass? lower surface of the ceiling 22 to the topsurfaces of the biscuit on the conveyor 5. To permit variation of thisbaking factor, the ceiling 22 is made adjustable toward and from theconveyor 5. For

this purpose, the entire ceiling structure, comprising the immediateceiling 22, the chamber 33,

' through the top wall of the structure in which the screws are squaredin cross section and fitted into square holes in the top wall, toprevent rotation of the screws. Thence the screws extend upwardlythrough part of the framework of the apparatus to receive adjusting nuts56, 56. The latter are formed with bevel gears to engage mating gears58, 5B fixed at opposite ends of a shaft '59 which carries a hand wheel50. One of the screws 55 has a right-hand thread and the other aleft-hand thread. Upon turning the hand wheel 50 the adjusting nuts 51,5'! are rotated to elevate or lower the ceiling structure, thereby toregulate the distance between the conveyor 5 and the reflecting orradiating surface of the,

ceiling 22.

At intervals along the length of the conveyor 5 brackets 62-, 62 areprovided, in pairs arranged transversely of the oven chamber, onepair-being shown in Fig. 2. there shown, as between the othercorresponding brackets, shafts B3, 64 are mounted which carry idlerollers to support the upper and lower runs of the conveyor.

In the practiceof the method and the use of the apparatus illustrated inthe foregoing description, numerous important purposes are achieved. Therelatively heavy concentration of .metal in the conveyor 5 supplies adesirable heatretaining capacity so that when the conveyor is heated tothe desired degree, prior to the intro duction of the comparativelycolddough biscuit, the content of heat in the metal sufiices emcientlyto give to the dough the desired quick spring, 1. e., the expansion ofthe .leavening gases and the vaporization of a considerable part ofthemoisture in the dough. If a substantially lesser body of metal wereemployed, its heat content would be too quickly andununiformlydissipated upon contact with the colder dough pieces, with the resultthat the application of heat to the dough would not be suflicientlyuniform or continuous to produce the desired spring.

By the use of a conveyor structure such as that typified in Fig. 4, andcharacterized by the described concentration of metaL the initial quick"spring of the dough is promoted not only by the high heat content ofthemetal which is communicated to the dough mainly by conduction andradiation, but also'by convection currents originating at the burners'and passing through the interstices of the conveyor to impinge againstthe bottom surfaces of the dough, and to encircle each dough piece whenthe pieces are spaced apart on the conveyor, and additionally by directradiation from the burners 25 also through the interstices in the.conveyor to the bottom surface of the dough and around the edges of thedough pieces. In the baking of some kinds of dough. a critical time'inthe operation arrives when the. cold dough is first deposited upon theconveyor. According to this invention, at that critical time the threemodes of heat communication are brought to bear with the highest em-Between the brackets 62, 62.

ciency; i, e., conduction, convection and radiation. At the same time,because of the'meshed structure of the conveyor, a very largeaggregatesurface of the metal is brought into play, and this serves thetwo-fold purpose that the heat content of the conveyor is speedilyreplenished against the tendency of the cold dough to consume the heat,and also the multiple surfaces of the metal radiate heat and initiateconvection currents immediately adjacent the dough. In this way, thereis an important practical coordination of the meshed conformation of theconveyor which exposes multiplied areas of metal,

the very substantial body of metal of which the at'the critical time ofthe deposit of the dough the proper temperature of the conveyor'may beinsured.

Another factor is the radiation and reflection of heat downwardly fromthe ceiling 22, and the facility with which moisture may be withdrawnand its withdrawal regulated at different points in the oven through thevents 30, and 3|, 3| controlled by the valve plates 31 and 45.

It has been recognized in the prior art that substantial bodies ofheat-retaining metal are desirable to be used in oven plates and thelike, to promote the quick initial spring of some kinds of biscuitdough. But mechanical limitations surrounding the use 'of endlessconveyors of the steel-band type, have obstructed the use of bandmetalthick enough to supply an adequate heatretaining character. For example,when an endless steel band is used as an oven conveyor, it must travelaround the drums whose diameters must be appropriate to the thickness ofthe band. It is a generally accepted rule that an endless steel conveyorcan be driven practicably over drums having diameters approximately 1000times the thickness of the band. Considerations of space and arrangementprohibit the use of drums of too great diameter. Onthe other hand, ithas been generally considered that metal oven plates (for soda crackers,for instance) should be of about 10 gauge thickness,--i. e., about .14inch thick, to have the needed heat-retainin capacity. If it wereattempted to use thisthickness of metal in an endless band, the latterwould require drums having diameters of about leiinches or more than 11feet, which wouldbe prohibitive. According to this invention, however,an adequately heavy body of metal in meshed or equivalent articulatedform has an abundant heat-retaining capacity in an endless bandconveyor, and at the same time has such free flexibility as to permitthe useof drums of relatively small diameter. If drums of like diam--segregated dough-biscuit but the invention may be used with greatadvantage in baking peels or sheets of dough.

I claim:

- 1. Apparatus for baking biscuit comprising, in combination, aband-oven chamber; a traveling oven-band for supporting dough in saidchamber, said band formed of flexibly articulated meshes of heavy metalwire weighing approximately 5 to 8 pounds per square foot of the band,whereby the metal of the band at baking temperature'has a thermalcapacity sufiicient to produce quick spring in dough, and said bandhaving a multitude of interstices through the meshed wire interruptingthe dough-supporting surface of the 1 band and exposing a substantialproportion of the lower face of the dough; a source of heat for heatingsaid band and supplying heat through said interstices to the exposedparts of the lower dough surface; means supporting the band for travelin the open chamber; and means for moving the band.

2. Apparatus for baking biscuit comprising, in combination, an ovenchamber; a dough-support for said chamber formed of metal having athermal capacity, per unit of area, approximating that of a steel ovenplate of about 10 U. S. gauge, whereby the support at baking temperaturesupplies heat continuously to the dough by conduction and said supporthaving interstices passing therethrough interrupting thedough-supporting surface and exposing a substantial proportion of thelower face of the dough; and a source of heat for heating the support.

3. Apparatus for baking biscuit comprising, in combination, an ovenchamber; a. dough-support for said chamber formed of metal having athermal capacity approximately equivalent to that of steel mesh weighingabout 5 pounds or more per 0 square foot, whereby to produce quickspring in dough for soda crackers and the like, and said support havinginterstices passing therethrough interrupting the dough-supportingsurface and exposing a substantial proportion of the lower face of thedough; and a source of heat for heating the support.

4. Apparatus for baking biscuit comprising, in combination, an ovenchamber; a dough-support in said chamber formed of metal having athermal capacity approximately equivalent to that of steel mesh weighingabout 5 pounds or more per square foot, and said support having aninterrupted dough-supporting surface supplyingpaa sages for the escapeof moisture from the lower face of the dough; and a source of heat forheating the support.

5. Apparatus for baking biscuit comprising,'in combination, an ovenchamber; a dough-support in said chamber formed of metal having athermal capacity approximately equivalent to that of steel mesh weighingabout 5 pounds or more per square foot, and said support having aninterrupted dough-supporting surface supplying passages for the escapeof moisture from the lower face of the dough; a source of heat forheating the support; means to permit the removal of moisture from theoven chamber; and means to vary the direction of movement of moisture inthe oven chamber.

6. Apparatus for baking biscuit comprising, in

combination, an oven chamber; a dough-support in said chamber formed ofmetal having a thermal capacity approximately equivalent to that ofsteel mesh weighing about 5 pounds or more per square foot, and saidsupport having an interrupted dough-supporting surface supplyingpassages for the escape of moisture from the lower face of the dough; asource of heat for heating the support; and means for regulating thevolume of the interior of the chamber.

